MOSCOW (AFP) - Tens of thousands of Russian opposition supporters thronged the streets of Moscow on Saturday to keep up the momentum of their challenge to Vladimir Putin’s rule four months into his new mandate.A diverse sea of protestors brandishing the red flags of socialism, nationalist tricolours or liberal slogans filled the avenue in Moscow named after the great Soviet physicist and celebrated dissident Andrei Sakharov.Some 40,000 people turned out for the “March of Millions”, according to an AFP estimate, in line with organisers’ expectations but down on the massive first protests that first rocked Moscow in December and rallied over 100,000.Police and organisers gave vastly different estimates, accusing each other of not knowing how to count. Police said that 14,000 people joined the protest, but organiser and far-left leader Sergei Udaltsov saw at least 150,000.Waving nationalist flags, brandishing placards calling for early elections or wearing T-shirts in support of jailed punk band Pussy Riot, protestors hoped to build on the anger created by fraud-tainted elections and Putin’s 12-year grip on power.The protest also tried to put a greater emphasis on social justice than past actions. “Power to the millions not to the millionaires!” read one slogan.Split between liberals, nationalists and the extreme left, the anti-Putin opposition has been struggling with its own divisions and accusations it lacks any coherent message beyond hostility to the Kremlin.The most charismatic opposition leader, anti-corruption crusader Alexei Navalny, told the protestors to prepare for a long haul to challenge Putin and turn up to rallies as if they were going to work.“All that we are asking for is something simply called freedom, nothing more than equality, simply human dignity.“No one will give us freedom except for ourselves. Hope and perseverance will bring us victory,” he declaimed to cheers from the crowds.Udaltsov, the leader of the radical Left Front, told the crowds: “We must gradually conquer the streets. We are not leaving!”Sporting dark sunglasses and a black bomber jacket, he urged supporters to wear shades to show their hatred of the authorities.